On 08/12/14 22:42, Bjorn Andersson wrote:
> On Wed, Dec 3, 2014 at 8:18 AM, Marc Zyngier <marc.zyngier@xxxxxxx> wrote:
>> There is a number of cases where a kernel subsystem may want to
>> introspect the state of an interrupt at the irqchip level:
>>
>> - When a peripheral is shared between virtual machines,
>> its interrupt state becomes part of the guest's state,
>> and must be switched accordingly. KVM on arm/arm64 requires
>> this for its guest-visible timer
>> - Some GPIO controllers seem to require peeking into the
>> interrupt controller they are connected to to report
>> their internal state
>>
>> This seem to be a pattern that is common enough for the core code
>> to try and support this without too many horrible hacks. Introduce
>> a pair of accessors (irq_get_irqchip_state/irq_set_irqchip_state)
>> to retrieve the bits that can be of interest to another subsystem:
>> pending, active, and masked.
>>
>> - irq_get_irqchip_state returns the state of the interrupt according
>> to a parameter set to IRQCHIP_STATE_PENDING, IRQCHIP_STATE_ACTIVE,
>> IRQCHIP_STATE_MASKED or IRQCHIP_STATE_LINE_LEVEL.
>> - irq_set_irqchip_state similarly sets the state of the interrupt.
>>
>> Signed-off-by: Marc Zyngier <marc.zyngier@xxxxxxx>
>
> With the addition of actually assigning err to something useful in the
> setter below:
>
> Reviewed-by: Bjorn Andersson <bjorn.andersson@xxxxxxxxxxxxxx>
> Tested-by: Bjorn Andersson <bjorn.andersson@xxxxxxxxxxxxxx>
>
>> diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
>
> [..]
>
>> +/**
>> + * irq_set_irqchip_state - set the state of a forwarded interrupt.
>> + * @irq: Interrupt line that is forwarded to a VM
>> + * @which: State to be restored (one of IRQCHIP_STATE_*)
>> + * @val: Value corresponding to @which
>> + *
>> + * This call sets the internal irqchip state of an interrupt,
>> + * depending on the value of @which.
>> + *
>> + * This function should be called with preemption disabled if the
>> + * interrupt controller has per-cpu registers.
>> + */
>> +int irq_set_irqchip_state(unsigned int irq, enum irqchip_irq_state which,
>> + bool val)
>> +{
>> + struct irq_desc *desc;
>> + struct irq_data *data;
>> + struct irq_chip *chip;
>> + unsigned long flags;
>> + int err = -EINVAL;
>> +
>> + desc = irq_get_desc_buslock(irq, &flags, 0);
>> + if (!desc)
>> + return err;
>> +
>> + data = irq_desc_get_irq_data(desc);
>> +
>> + do {
>> + chip = irq_data_get_irq_chip(data);
>> + if (chip->irq_set_irqchip_state)
>> + break;
>> +#ifdef CONFIG_IRQ_DOMAIN_HIERARCHY
>> + data = data->parent_data;
>> +#else
>> + data = NULL;
>> +#endif
>> + } while (data);
>> +
>> + if (data)
>> + chip->irq_set_irqchip_state(data, which, val);
>
> err =
Ah, that will teach me to write test code that actually checks the
return value! :-)
Thanks for the fix and the tags.
M.
--
Jazz is not dead. It just smells funny...
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